1. Field of the Invention
This invention relates to a fuel pump apparatus which sucks fuel from a fuel tank and pressurizes and supplies the fuel to an engine.
2. Description of Background Art
As a technique for supplying fuel to an intake system of an engine, a technique of pressurizing fuel from a fuel tank by means of a pump and feeding the pressurized fuel to an engine has been placed into practical use (refer to, for example, Japanese Patent Laid-Open No. 2008-213630 (FIG. 5(b)).
As shown in FIG. 5(b) of Japanese Patent Laid-Open No. 2008-213630, a fuel pump apparatus (81) (reference character in parentheses represents a reference character used in Japanese Patent Laid-Open No. 2008-213630. This similarly applies also to the following description) includes a pump (86), a pump pre-filter (87) provided at an intake port of the pump (86) for removing foreign matter included in fuel, a tube member (83) for accommodating the pump (86) and the pump pre-filter (87) therein, and a lid member (82) for closing up an upper opening of the tube member (83). The lid member (82) includes a joint portion (82c) serving as an inlet port for fuel from within a fuel tank, and a joint portion (82a) serving as an outlet port of fuel to an intake system of an engine.
Incidentally, if the fuel pump apparatus (81) is mounted on a vehicle represented by an off road bike which travels on an unpaved road, then foreign matter such as sand is sometimes mixed into fuel. Although the mixed foreign matter is caught by the pump pre-filter (87), if the amount of foreign matter becomes great, then the pump pre-filter (87) is clogged, and this drops the pump flow rate.
A countermeasure for preventing the pump flow rate from dropping has been proposed (refer to, for example, Japanese Patent Laid-Open No. 2006-182154 (FIGS. 2 and 4)).
As shown in FIG. 2 of Japanese Patent Laid-Open No. 2006-182154, in a fuel pump apparatus (10) (numeral in parentheses represents a reference character used in Japanese Patent Laid-Open No. 2006-182154. This similarly applies also to the following description), a lid member (11) is removably attached to a tube member (12) in which a pump (13) and a pump pre-filter (18) are accommodated. Since the lid member (11) is removably attached, the pump pre-filter (18) can be taken out by removing the lid member (11).
By taking out, cleaning and returning the pump pre-filter (18), a drop of the pump flow rate can be prevented.
However, in the technique illustrated in FIG. 2 of Japanese Patent Laid-Open No. 2006-182154, when the pump pre-filter (18) is to be taken out, it is necessary to pull out the lid member (11), pump (13) and accessories in their entirety from the tube member (12) and carry out working, and therefore, the maintenance performance is not high.
A technique which eliminates the requirement for taking out of the pump pre-filter (18) is shown in FIG. 4 of Japanese Patent Laid-Open No. 2006-182154.
As shown in FIG. 4 of Japanese Patent Laid-Open No. 2006-182154, a fuel filter (41) is interposed midway of a fuel hose (32) which connects a fuel tank (40) and the fuel pump apparatus (10) to each other. Since foreign matter in fuel is removed by the fuel filter (41), clogging of the pump pre-filter can be prevented. With this structure, there is no requirement for taking out of the pump pre-filter.
In other words, by removing the exposed fuel filter (41) from the fuel hose (32), exchange and cleaning can be carried out, and improvement of the maintenance performance can be anticipated.
However, in the technique disclosed in FIG. 4 of Japanese Patent Laid-Open No. 2006-182154, since the fuel filter (41) is exposed to the outside, a protective case for the purpose of a countermeasure against a flying stone is required. In addition, a stay for attaching the fuel filter to a vehicle body is required separately.
Therefore, a technique which does not require a protective case for protecting a fuel filter or a stay for attaching a fuel filter to a vehicle body is demanded.